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54 lines
2.4 KiB
Plaintext
54 lines
2.4 KiB
Plaintext
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<chapter id="howitworks">
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<title>How it works</title>
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<sect1 id="howitworks-overview">
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<title>Overview</title>
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<para>PolicyKit has a simple way of working, but it requires some
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design changes from the applications that want to use it to request
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passwords.</para>
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</sect1>
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<sect1 id="howitworks-problem">
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<title>The problem</title>
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<para>In GUI applications the common way to gain root privileges is to start
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it as root, but there are several security risks in doing this method and
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it does not allow a good actions mapping. There is no way to separate actions
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like package-install of system-upgrading.
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All the users who want to use it must have the root password. Another common
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approach is using sudo but once you start an application with sudo you will
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have all the rights the root user will have.
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If for example the GUI application has a dialog to select files that dialog
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is running as root which means that the user might be able to delete any file
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on his machine or even coping others user files.
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</para>
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</sect1>
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<sect1 id="howitworks-solution">
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<title>The solution</title>
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<para>With PolicyKit this problem is solved. The application in question
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just need to separate the privileged code into another application,
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often called helper (which will not have a GUI), then maps the desired
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actions into a <quote>.policy</quote> file. PolicyKit then loads this file
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and it can now authenticate applications to use those actions.
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The use of &DBus; activated applications is the best if not the only,
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way of putting an helper application to run with root privileges.</para>
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<para>With this design the GUI application calls an action of the helper
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application through &DBus;, which will start the helper with root privileges,
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and informing it which action was requested and which application has requested
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it. The helper application now calls the PolicyKit agent to see if that application
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can do the given task, the helper should report if it could do the requested action.
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In case the helper saw that the application didn't have enough rights the GUI
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will then need to ask PolicyKit to obtain an authorization.</para>
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<para>When PolicyKit receives the request to obtain an authorization it issues an
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available Agent, which might happen to be &policykit-kde; if available. After a successful
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authentication the GUI application needs to call the helper repeating the
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same operation again.</para>
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</sect1>
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</chapter>
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